組織學(xué)與胚胎學(xué)：消化腺

消化腺DigestiveGland

消化腺大消化腺小消化腺：小唾液腺、胃腺、腸腺等唾液腺胰臟肝臟一、唾液腺

腮腺一對下頜下腺一對舌下腺一對導(dǎo)管開口于口腔大唾液腺Figure1.Majorsalivaryglands.About90%ofsalivaisproducedbythreebilateralpairsofsalivaryglands:theparotid,submandibular,andsublingualglands.Locationsandrelativesizesoftheseglandsareshownherediagrammatically.Theseglandsplusmicroscopicsalivaryglandsthroughouttheoralmucosaproduce0.75to1.50Lofsalivadaily.（一）大唾液腺的一般結(jié)構(gòu)

復(fù)管泡狀腺腺泡（alveoli）導(dǎo)管（duct）Figure2.Epithelialcomponentsofasubmandibularglandlobule.Thesecretoryportionsarecomposedofpyramidalserous(lightblue)andmucous(lightbrown)cells.Serouscellsaretypicalprotein—secretingcells,withroundednuclei,accumulationofroughERinthebasalthird,andanapexfilledwithprotein—richsecretorygranules.Thenucleiofmucouscells,flattenedwithcondensedchromatin,arelocatednearthebasesofthecells.Theshortintercalatedductsarelinedwithcuboidalepithelium.Thestriatedductsarecomposedofcolumnarcellswithcharacteristicsofion—transportingcells:basalmembraneinvaginationswithmitochondrialaccumulations.Myoepithelialcellsareshownintheserousacini.1、腺泡（1）漿液性腺泡（serousalveoli）：漿液性腺細(xì)胞組成，分泌物稀薄，含淀粉酶和少量粘液。

Figure3.Parotidgland.Thelargeparotidglandconsistsentirelyofserousaciniwithcellsproducingamylaseandotherproteinsforstorageinsecretorygranules.(a):Micrographofaparotidglandshowsdenselypackedserousacini(A)withducts.Secretorygranulesofserouscellsareclearlyshowninthisplasticsection,aswellasbothanintercalatedduct(ID)andstriatedduct(SD),bothcuttransversely.X400.PT.(b):Striationsofaduct(SD)arebetterseenhere,alongwithaseptum(CT)andnumerousserousacini(A).Theconnectivetissueoftenincludesadipocytes.X200.H&E.（2）粘液性腺泡（mucousalveoli）：由粘液性腺細(xì)胞組成，分泌物粘稠，主要為粘液。

（3）混合性腺泡（mixedalveoli）：由漿液性腺細(xì)胞和粘液性腺細(xì)胞共同組成。大部分混合性腺泡主要由黏液性腺細(xì)胞組成，幾個(gè)漿液性腺細(xì)胞排列成半月形帽狀結(jié)構(gòu)附著在腺泡的底部或末端，故稱漿半月。

Figure4.Ultrastructureofserousandmucouscells.Amicrographofamixedacinusfromasubmandibularglandshowsbothserousandmucouscells.Mucouscells(upperareashownhere)havelarge,hydrophilicgranuleslikethoseofgobletcells.Serouscells(lowerarea)havesmall,densegranulesthatstainmoreintenselywithmoststains.X2500.(Withpermission,fromJohnD.Harrison,DepartmentofOralPathology,King’sCollege,London.)2、導(dǎo)管（duct）閏管（intercalatedduct）：單層立方或單層扁平上皮，細(xì)而短，與腺泡相連。紋狀管（striatedduct）：單層高柱狀上皮，管徑粗，與閏管相延續(xù)。小葉間導(dǎo)管（interlobularduct）：單層柱狀或假復(fù)層柱狀上皮，管徑粗，由紋狀管匯集而成，穿行于小葉間結(jié)締組織內(nèi)。總導(dǎo)管（pancreaticduct)：近口腔處為復(fù)層扁平上皮,由小葉間導(dǎo)管匯合成。Figure5.Striatedducts.(a):Thislightmicrographofastriatedduct(SD)showsveryfaintpinkstriationsinthebasalhalfofthecolumnarcells.Thestriationsareproducedbymitochondrialocatedinthefoldsofthelateralcellmembrane.X200.H&E.(b):SEMindicatesthattheapicalendsofthecellsarejoinedtogethernearthesmalllumen(L),withinterdigitatingfoldsofcellmembranebestdevelopedatthebasalend(B).X4000.(c):ThisSEMshowsthebases(B)ofseveralsuchcellswiththebasallaminaremoved,revealingtheextensiveinterlockingoffoldedmembranebetweenneighboringcells.Mitochondriabetweenthefoldssupplyenergyformembraneionpumpsandionuptakefromsalivaisrapidandefficient.X4000三種唾液腺的結(jié)構(gòu)特點(diǎn)腺泡閏管紋狀管分泌物腮腺純漿液腺較長有淀粉酶多，粘液少下頜下腺混合腺，較短較長粘液多，以漿液性淀粉酶少腺泡為主舌下腺混合腺，無不明顯以粘液以粘液性、為主?；旌闲韵倥轂橹?。Figure6.Submandibularglandandsublingualgland.(a):Submandibularglandisamixedserousandmucousgland(serouscellspredominate)andshowswell—stainedcellsinserousacini(A)andinserousdemilunes(S)andpale—stainingmucouscells(M)groupedastubulesinthistubuloacinargland.Smallintralobularducts(ID)draineachlobule,butthesearenotcomposedofcolumnarcellswithwell—developedstriations.X340.H&E.(b):Sublingualglandisamixedbutlargelymucousglandwithatubuloacinararrangementofpoorlystainedmucouscells(M).Smallintralobularducts(ID)areseeninconnectivetissue,aswellassmallfasciclesoflingualstriatedmuscle(SM).X140.H&E.二、胰腺（pancreas）Figure7.Pancreasandduodenum.(a):Themainregionsofthepancreasareshowninrelationtothetwopancreaticductsandtheduodenum.(b):Micrographsshowapancreaticisletandseveralpancreaticacini.X75andX200.H&E.

表面覆以薄層結(jié)締組織被膜，被膜的結(jié)締組織伸入腺內(nèi)將實(shí)質(zhì)分隔為許多分界不明顯的小葉。腺實(shí)質(zhì)由外分泌部和內(nèi)分泌部兩部分組成。

外分泌部：漿液性復(fù)管泡狀腺，分泌胰液，在小腸消化食物過程中起重要作用。

內(nèi)分泌部：散在于外分泌部之間的細(xì)胞團(tuán)，也叫胰島（pancreaticislet），參于糖代謝調(diào)節(jié)。Figure8.Pancreas.Lowpowerviewofpancreasincludesseveralislets(I)surroundedbymanyserousacini(A).Thelargerinterlobularducts(D)arelinedbysimplecolumnarepithelium.Theductsandbloodvessels(V)arelocatedinconnectivetissue,whichalsoprovidesathincapsuletotheentireglandandthinseptaseparatingthelobulesofsecretoryacini.X20.H&E.1、腺泡（acinus）：漿液性腺泡，腺細(xì)胞具合成蛋白質(zhì)的結(jié)構(gòu)特點(diǎn)，分泌胰蛋白酶原、胰凝乳酶原、羧肽酶、胰淀粉酶、胰脂肪酶、DNA酶、RNA酶等多種消化酶，腺泡腔面可見泡心細(xì)胞，是延伸到腺泡腔內(nèi)的閏管上皮細(xì)胞。

（一）外分泌部人胰腺光鏡圖HE染色Figure16–9.Pancreaticacini.(a):Micrographofexocrinepancreasshowstheserous,enzyme—producingcellsarrangedinsmallacini(A)withverysmalllumens.Aciniaresurroundedbysmallamountsofconnectivetissuewithfibroblasts(F).Eachacinusisdrainedbyanintercalatedductwithitsinitialcells,thecentroacinarcells(arrow),insertedintotheacinarlumen.X200.H&E.(b):Thediagramshowsthearrangementofcellsmoreclearly.Undertheinfluenceofsecretin,thecentroacinarandothercellsofthesesmallductssecreteacopiousHCO3?—richfluidthathydratesandalkalinizestheenzymaticsecretionsoftheacinarcells.Pancreaticacinilackmyoepithelialcellsandtheirintercalatedductslackstriations.Figure10.Pancreaticacinarcells.TEMofapancreaticacinarcellshowsitspyramidalshapeandtheround,basalnucleus(N)surroundedbycytoplasmpackedwithcisternaeofroughER(RER).TheGolgiapparatus(G)issituatedattheapicalsideofthenucleusandisassociatedwithcondensingvacuoles(C)andnumeroussecretory(zymogen)granules(S).Thesmalllumen(L)oftheacinuscontainsproteinsrecentlyreleasedfromthecellbyexocytosis.ExocytosisofdigestiveenzymesfromsecretorygranulesispromotedbyCCK,releasedfromtheduodenumwhenfoodentersthatregionfromthestomach.X8000.閆管：較長，單層扁平或立方上皮。小葉內(nèi)導(dǎo)管：較粗，單層立方上皮。小葉間導(dǎo)管：較粗，為單層立方或矮柱狀上皮。主導(dǎo)管：單層高柱狀上皮，含杯狀細(xì)胞和內(nèi)分泌細(xì)胞。2、導(dǎo)管（duct）（三）內(nèi)分泌部（胰島pancreasislet）

Figure20–17.Pancreaticislets.Pancreaticisletsareclumpedmassesofpale—stainingendocrinecellsembeddedintheexocrineacinartissueofthepancreas.(a):Alow—magnificationmicrographthroughthetailofthepancreasrevealsmanyisletsstainedlighterthanthesurroundingtissue.Thewhitespotsareadipocytesinfinepancreaticsepta,likethoseoftheadiposetissueoutsidethegland.X12.5.H&E.(b):Micrographofanenlargedisletshowingitscapillarysystem.Severalarteriolesentereachislet,branchintofenestratedcapillaries(C)amongtheperipheralisletcells,thenconvergecentrallybeforeleavingtheisletasefferentcapillariescarryingbloodtotheacinisurroundingtheislet.Thislocalvascularsystemallowsspecificislethormonestohelpcontrolsecretionofotherisletcellsandtheneighboringacini.X40.H&E.(c):WithH&Estainingallcellsofanisletappearsimilar,althoughslightdifferencesincellsizeandbasophiliamaybeapparent.Capillaries(C)arealsoapparent.X55.H&E.(d):Anisletpreparedwithamodifiedaldehydefuchsinstainshowsgranulesintheperipheralαcellsareadeepbrownishpurpleandthecentralβcellsgranulesarebrownishorange.Reticulinconnectivetissueoftheisletcapsuleandalongthecapillariesstainsgreeninthispreparation.Immunohistochemistrywithantibodiesagainstthevariousisletpolypeptidehormonesallowsdefinitiveidentificationofeachisletcelltype.X300.Modifiedaldehydefuchsinandlightgreen.(e):Diagramshowsthefourmajorislethormonesandthecellssecretingthem:αcellsmakingglucagon,βcellsmakinginsulin,dcellsmakingsomatostatin,andF(PP)cellsmakingpancreaticpolypeptide.(Figure20–17d,withpermission,fromArthurA.Like,DepartmentofPathology,UniversityofMassachusettsMedicalSchool,Worcester.)1、A細(xì)胞（20%）：細(xì)胞較大，多邊形，分布于胰島周邊，分泌胰高血糖素，可促糖原→葡萄糖，并抑制糖原合成，致使血糖升高。分泌顆粒2、B細(xì)胞（75%）：為胰島的主要細(xì)胞，位于胰島的中央部。分泌胰島素，其作用與胰高血糖素相反，促葡萄糖→糖原，或葡萄糖→脂肪，故使血糖降低。分泌顆粒3、D細(xì)胞（5%）：數(shù)量少，分散在胰島周邊部，A、B細(xì)胞之間。D細(xì)胞分泌生長抑素（somatostatin），以旁分泌方式作用于鄰近的A、B、PP等細(xì)胞，調(diào)節(jié)其分泌功能。分泌顆粒4.PP細(xì)胞：數(shù)量很少，可分泌胰多肽，抑制胰液分泌、胃腸運(yùn)動(dòng)及膽囊收縮。5．D1細(xì)胞：較少，主要分布在胰島的周邊部。D1細(xì)胞分泌血管活性腸肽（VIP）。三、肝臟（liver）：最大的腺體Figure11.Liver.Alargeorganintheupperrightquadrantoftheabdomen,immediatelybelowthediaphragm,theliveriscomposedofthousandsofpolygonalstructurescalledhepaticlobules,whicharethebasicfunctionalunitsoftheorgan.(a):Diagramshowsasmallcentralveinprojectingthroughthecenterofeachhepaticlobuleandseveralsetsofbloodvesselsdefiningtheperiphery.Theperipheralvesselsaregroupedprimarilyinconnectivetissuecomprisingtheportaltracts,whichusuallyincludeabranchoftheportalveinandabranchofthehepaticartery,aswellasabranchofthebileduct.Thesecomprisetheportaltriad.(b):Bothbloodvesselstoeachlobulegiveoffsinusoids,whichrunbetweenplatesofhepatocytesanddrainintothecentralvein.(c):Micrographshowingcomponentsoftheportaltriad.X220.H&E.肝(Liver)：是機(jī)體最大的腺體，表面大部由漿膜覆蓋。肝實(shí)質(zhì)由若干肝小葉構(gòu)成，小葉間有結(jié)締組織和門管區(qū)。肝臟除消化功能外，還有多種生理功能。肝臟功能：1、分泌膽汁，有助于脂肪的消化和吸收2、參與物質(zhì)代謝，合成多種蛋白質(zhì)和脂類

3、解毒、防御功能

4、胚胎時(shí)期具造血功能肝臟的基本結(jié)構(gòu)和功能單位。Figure16–12.Hepaticlobule.Cuttransverselyhepaticlobulesarepolygonalunitsshowingplatesofepithelialcellscalledhepatocytesradiatingfromacentralvenule(C).(a):Hepaticlobuleofsomemammals,suchasthepig,aredelimitedonallsidesbyconnectivetissue.(b):Hepaticunitsofhumanshavemuchlessconnectivetissueandtheirboundariesaremoredifficulttodistinguish.Inallcasesperipheralconnectivetissueofportalareaswithmicrovasculatureandsmallbileduct(D)branchescanbeseenandinhumansasinothermammalsthesearepresentattheboundariesbetweentwoormorehepaticlobules.Thevesselsnearthebileductsbranchesareavenule(V)offtheportalveinandanarteriole(A)offthehepaticartery.BothX150.H&E.肝細(xì)胞以中央靜脈為中心，向周圍呈放射狀排列成板狀結(jié)構(gòu)，稱肝板。在切片中，肝板的斷面呈索狀，稱肝索。肝板之間的空隙為肝血竇，血竇經(jīng)肝板上的孔互相通連，形成網(wǎng)狀管道相鄰肝細(xì)胞膜凹陷形成的微細(xì)管道稱膽小管，它以盲端起始于中央靜脈附近，其主干在肝板內(nèi)呈放射狀走向肝小葉周邊，并分支環(huán)繞每個(gè)肝細(xì)胞，在肝板內(nèi)構(gòu)成網(wǎng)格狀細(xì)管。肝細(xì)胞分泌的膽汁進(jìn)入膽小管內(nèi)。1、中央靜脈：內(nèi)皮不完整，有許多小孔，通肝血竇。2、肝板：以中央靜脈為中心，向四周放射狀排列。由單行肝細(xì)胞組成，相鄰肝板可吻合連接成迷路樣結(jié)構(gòu)。Figure13.Hepaticlobulemicrovasculature.(a):Thehepaticlobule’scentralvein(CV)isactuallyavenuleconsistingoflittlemorethananendothelialtubewithsmallersinusoids(S)cominginfromalldirections.X200.H&E.(b):Peripheralportalareascontainmoreconnectivetissueandarethesitesoftheportaltriad:aportalvenule(PV),anarteriole(A)branchingoffthehepaticartery,andoneortwobranchesofthebileduct(D).Bloodflows(arrow)fromthesearteriolesandvenulesintothesinusoidsbetweentheplatesofhepatocytesthatruntothecentralvenule.Intheportalareathebileductulesarelinedbysimplecuboidalepithelium.X400.H&E.(c):Reticulin(collagentypeIII)fibersrunningalongtheplatesofhepatocytesarethemajorsupportforthesinusoidsandcentralvenules.Mostconnectivetissueintheliverisfoundintheseptaandportaltracts.X400.Silver.3、肝血竇：位肝板之間，通過肝板上的孔洞相互通連。特點(diǎn)是：1）內(nèi)皮有孔，無隔膜，無基膜，通透性很大。

2）竇腔內(nèi)有枯否氏細(xì)胞。枯否氏細(xì)胞特殊染色枯否氏細(xì)胞的作用：（1）吞噬、清除從胃腸進(jìn)入門靜脈的細(xì)菌、病毒和異物。（2）吞噬、清除衰老、破碎的紅細(xì)胞和血小板等。（3）識(shí)別腫瘤細(xì)胞特異性抗原及抑制和殺傷腫瘤細(xì)胞。Figure16–14.Hepaticsinusoids.Nutrient—richbloodfromtheportalveinandoxygen—richbloodfromthearteriolemixinthesinusoidsrunningbetweentheplatesofhepatocytesfromtheportalareastothecentralvenules.Moleculesinthebloodareprocessedmainlybythehepatocytes,butothercellsinornearthesinusoidsarealsoimportant.Specializedstellatemacrophages,oftencalledKupffercells,areboundtotheendotheliallumenofthesinusoids,wheretheydetectandphagocytoseeffeteerythrocytes.(a):StellatemacrophagesareseenasblackcellsinaliverlobulefromaratinjectedwithparticulateIndiaink.X200.H&E.(b):Inthisplasticsection,stellatemacrophages(M)areseeninthesinusoid(S)betweentwogroupsofhepatocytes(H).Theyarelargerthantheflattenedendothelialcells(E).Betweentheendotheliumandthehepatocytesisathinspacecalledtheperisinusoidalspace(PS),inwhicharelocatedfibroblasticfat—storingcells(F),orItocells,thatmaintaintheverysparseECMofthiscompartmentandarealsospecializedforvitaminAstorageinsmalllipiddroplets.Thesecellsarenumerousbutaredifficulttodemonstrateinroutinehistologicalpreparations.Iftheirlipiddropletsbecomeverylargeorabundant,thefat—storingcellsresembleadipocytes.X750.PT.Figure16–15.Ultrastructureofthesinusoidwall.SEMoftheluminalsurfaceoftheendotheliumliningasinusoidinlivershowsgroupedfenestrations.Attheborderareseencutedgesoftheendothelialcell(E)inthisdiscontinuoussinusoidandhepatocytes(H).Betweenthesetwocellsisthethinperisinusoidalspace(PS),intowhichprojectmicrovillifromthehepatocytessurface.Bloodplasmapassesfreelythroughthefenestrationsintotheperisinusoidalspace,wherethevoluminousmembraneofhepatocytesactstoremovemanyhighandlowmolecularweightbloodcomponentsandnutrientsforstorageandprocessing.Proteinssynthesizedandsecretedfromhepatocytes,suchasalbumin,fibrinogen,andotherbloodproteins,arereleasedintotheperisinusoidalspace.X6500.(Withpermission,fromEddieWisse,ElectronMicroscopyUnit,DepartmentofPathology,UniversityofMaastricht,TheNetherlands.)4、膽小管：相鄰肝細(xì)胞之間局部質(zhì)膜凹陷形成，腔內(nèi)有微絨毛，兩端有緊密連接等封閉。膽小管在肝板內(nèi)相互連接成網(wǎng)，將肝細(xì)胞分泌的膽汗導(dǎo)出肝小葉。Figure16–16.Ultrastructureofhepatocytesandbilecanaliculi.(a):TEMofhepatocytesshowsmallbilecanaliculi(BC)betweentwocells,withjunctionalcomplexesbindingthecellsfirmlyandtightlyatthesesites.Thebilecanaliculusisthesiteofexocrinesecretionbyhepatocytes.Thetwoadjoininghepatocytesextendshortmicrovilliandsecretebilecomponentsintothisspace.Thehepatocyteshavemanymitochondria(M),smallelectron—denseglycogengranules,andGolgicomplexes(G)andextendmorenumerousmicrovilliintotheperisinusoidalspace(PS),whichisthesitewherehepatocytesremoveandaddcomponentsinplasma.Theendothelialcell(E)liningthesinusoid(S)isalsoseen.X9500.(b):SEMofhepatocytes(H)br